I have a Diamond Membership, scheduled to renew on September 1, 2011. Yet, I have not been able to find any option which would allow me to renew at this point in time.

Should I just wait for chess.com to wait for chess.com to initiate the necessary action?  It's already August 15, 2011.

Unless you've stopped the process, I'm pretty sure it will auto renew.

i.e. On the day your present membership expires, the subscription will be drawn on your credit/debit card.

That's true. Alternatively, you can switch your membership to a yearly membership of either Gold or Platinum and then back again. This will charge you for a year's worth of diamond minus the 15 days you have left. Cheers :)

@PrwanEatsPrawn   Thank you once more.

It is actually the second time you've answered a question that was eluding me.  The first one was about How to access administrative tools.  All one had to do was take a better look at the existing menu :)

My thanks also go to Cry_Wolf:  that's another clever way to deal with the issue :)